Genomics rapidly evolving; unanswered questions remain

Submitted by admin on Wed, 04/28/2010 - 18:25

Hoard's Dairyman:

Genomics rapidly evolving; unanswered questions remain

Date:

Wed, 04/28/2010

The latest USDA genetic evaluations ushered in numerous changes just three months after January's major base change. Among them were imputed female evaluations and cow evaluation adjustments which put genomically tested female evaluations on a more even playing field with genomically tested male counterparts.

While all these changes might have been scientifically sound, they came as a surprise to most breeders since there was little advance notice regarding the changes prior to the April release. The lack of notice combined with the fact that the majority of genomically tested females dropped due to the corrections caused a great deal of frustration for owners of elite cattle. On top of that, cow adjustments created a multiple currency system which now sees genomically tested cows on a different genetic scale than those with traditional genetic evaluations. In our May 10 issue, AIPL scientists answer some questions regarding imputed proofs and cow adjustments. We are attaching a PDF of that article to help answer these questions. (May 10, 2010 pg 343).

At the latest Council on Dairy Cattle Breeding meeting in Baltimore, Md., on April 27 and 28, genomics continued to be a leading topic of conversation. Information shared with industry partners included:

• Full sibling do not share equal amount of genes from parents. In the past, it was thought that 50 percent of the genes came from the dam and 50 percent came from the sire. Genomic testing tells us that the number of genes in common between full siblings can range from 35 to 65 percent.

• The genomic evaluations for bulls with 99 percent reliability will change over time because scientists are learning more about the relationships within the Brown Swiss, Holstein, and Jersey breeds every month as more genomic data comes into the system.

• There are 50,119 animals with genotypes as of April 2010.

•North America is no longer in the lead for accuracy of genomic evaluations. A group of European countries (Germany, Holland, France, and Scandinavia — Denmark, Sweden, and Finland) have each contributed 4,000 genotypes for Holstein bulls to create a database of some 16,000 animals. The sharing system has created higher reliabilities — 5 percent higher — than those in the U.S. and Canada. German reliabilities are even a bit higher than other European countries because they tested an additional 1,000 bulls.

• The cow adjustments allowed genomically tested females to contribute to young bull evaluations. In Holsteins, the improvement in reliability went up 2.6 to 3.1 percent for yield traits. The improvement was greater for Jerseys at 7.7 to 9.4 percent. No adjustments were made in the Brown Swiss breed due to smaller population size.